1. Field of the Invention
The present invention relates to work machines, and more specifically to such machines that have hydraulic actuation systems incorporated therein.
2. Description of the Related Art
One of the most useful and popular work machines, particularly in the construction field, is a loader backhoe work machine. When operating under the loading function, machines of this type elevate, transport and unload granular material, soil or other items. In this function, the primary propulsion unit for the device is used for work machine movement along the ground, as well as powering the hydraulic actuators used to elevate and unload material. In the backhoe function, the machine is essentially stationary and the backhoe is used to penetrate the ground, removing scoops of soil and then moving it without the work machine being transported across the ground.
For certain types of lighter duty loader backhoe machines, it is desirable to use a smaller output propulsion unit. This allows the overall machine to be more cost effective and widely available for performing the loading and backhoe functions. With the smaller size propulsion unit, there is an issue when the unit is being used in the loader unit. Since the hydraulic pressure for the actuators of the loader system is provided by a pump driven off the propulsion unit, more power directed to the actuation system leaves less available for propulsion along the ground. This has a limiting factor on the usefulness of the machine for the dual functions.
Accordingly, what is needed in the art is a hydraulic actuation system for such a work machine in which the available power is effectively and economically balanced and split between the propulsion system and the actuation system.